It is doubtful that the current taxonomy provides a true picture of the diversity of the genus Aotus. Ruiz-Herrera et al. (2005) reported that cytogenetic studies have characterized 18 different karyotypes with diploid numbers ranging from 46 to 58 chromosomes. The taxonomy of the night monkeys essentially follows the revision by Hershkovitz (1983), with some modifications for the Colombian and Central American forms.

Justification:
This species is listed as Vulnerable as it is inferred to have undergone a population decline of more than 30% over the last three generations (24 years) due to habitat loss (ongoing threats include mining, population growth from immigration, and development in the area).

Aotus miconax is endemic to the Peruvian Andes, occurring south and east of the Río Marañón and west of the Río Huallaga (Hershkovitz 1983; Aquino and Encarnación 1994a). Butchart et al. (1995) recorded the species in the Cordillera de Colán, south of the Río Chiriaco, at altitudes from 1,730 to 2,400 m above sea level. In the south, it occurs along the left bank of the Río Huallaga in the Department of Huanaco, from the region of the Río Aguaytia (tributary of the Ucayali), north through San Martín into the Department of Amazonas, just south the Maranón (Aquino and Encarnación 1994a). This species has been recorded at elevations from 800 to 2,400 m asl.

Little is known about the population characteristics, but they are believed to be fairly common in remaining patches of forest. Aquino and Encarnación (1994b) reviewed population structure and densities for the genus.

This species occurs in humid and very humid lower montane cloud forests of eastern central Peru, where sympatric with Oreonax flavicauda (Butchart et al. 1995). Night monkeys typically occur in primary and secondary forest (including disturbed forest and selectively logged forest), seasonally flooded and terra firma, lowland forest, and submontane and montane (cloud forests) in Colombia and the Andes, above 800 m to 3,200 m above sea level (Hernández Camacho and Cooper 1976; Aquino and Encarnación 1994a; Defler 2004). Their sleeping sites include vine tangles and tree cavities like other species in the genus. This species can live in altered and secondary habitat. Aquino and Encarnación (1994b) reviewed the habitat and forest preferences of the genus.

Night monkeys are nocturnal: they are most active at dawn and dusk. The only exception is Aotus azarae azarae of the Chaco of southern Bolivia, Paraguay and Argentina, which is cathemeral (active during night and day). They are frugivorous; their diet includes fruit, nectar and flower (seasonally important for the A. a. azarae in the Chaco) , leaves, and small animals prey such as insects.

They are socially monogamous, living in small groups of an adult pair and offspring of different ages (infant, one or two juveniles and sometimes a subadult. In A. a. azarae, a significant number of adults range alone. They may be subadults that have left their natal groups or older adults which have been evicted from their groups by competitors (Fernandez-Duque and Huntington 2002; Fernandez-Duque 2004). Both sexes disperse. Males care for the infants (carry them) (Rotundo et al. 2002, 2005). Lone adults were observed by Villavicencio Galindo (2003) in northern Colombia. Night monkeys are territorial—groups occupy overlapping territories of 5-18 ha (depending on the species and location) (Wright 1978; Fernandez-Duque 2007). Wright (1994) and Fernandez-Duque (2007) review the behaviour and ecology of the genus.

Captive male A. lemurinus reach sexual maturity when 2 years old, and captive female A. vociferans and A. nancymaae first breed when 3-4 years old (Dixson 1983; Fernandez-Duque 2007). In the wild, male A. azarae reach adult weight only when about 4 years old, and age at first reproduction is about 5 years of age (Juárez et al. 2003; Fernandez-Duque 2004). A female A. azaraewas found to breed for the first time at 58 months of age (Fernandez-Duque et al. 2002). Single offspring are the rule. Wright (1985) recorded births between August and February for A. nigriceps in Peru (Manu National Park), and Aquino et al. (1990) indicated a birth season between December and March for A. nancymaae in north-eastern Peru. In the Argentinean Chaco, A. azaraeshows a peak of births between March and June (Fernandez-Duque 2007).

Butchart et al. (1995) reported that their main threat is deforestation in their restricted range. Threats include colonisation projects, road-building (the carretera central through the cloud forests of the region and new construction throughout their distribution), selective logging, deforestation, and forest fragmentation. Recently, mining companies have been granted concessions in areas where this species occurs and these growing mining operations including open pit mining represent an increasing threat to its habitat and habitat quality. They are not hunted for food, although Butchart et al. (1995) found one being kept as a pet.